已知tana/2=2求tan(a+π/4)

问题描述:

已知tana/2=2求tan(a+π/4)
2、(6sina+cosa)/3sina-2cosa的值

1.∵tan(a/2)=2∴tana=[2tan(a/2)]/{1-[tan(a/2)]^2}=(2×2)/(1-2^2)=-4/3∴tan(a+π/4)=[tana+tan(π/4)]/[1-tana×tan(π/4)]=(-4/3+1)/(1+4/3)=-1/72.原式=(6sina/cosa+cosa/cosa)/(3sina/cosa-2cosa/cosa)=(6tan...